Wrong keyWindow size in iPhoneOS 3.x for universal iPad/iPhone app with Base SDK 4.2

I have an iPad/iPhone app which I need to make compatible down to iPhoneOS 3.x

When I try to show a UIActionSheet in iPhone 3.x, the screen becomes darker and the action sheet is shown somewhere off the screen. The reason is that the key UIWindow has the wrong frame of {0, 0, 768, 1024}. On later iOS ve开发者_运维百科rsions the keyWindow has the expected size depending on the device.

Any ideas what the cause of this problem might be?

Thanks in advance...

Found the problem, posting here for future reference:

Since the project was first created for iPad, mainWindow.xib had a size of 1024x768. Changed it to be 480x320 and now everything works, every iOS and every device.

Hope this helps somebody!